In the prior art, a cover assembly, also known as a hood assembly, includes a rigid cover and a roll-up assembly, wherein the rigid cover is generally a foldable structure, which can be conveniently stored when the cover is not in use. Typically, the roll-up assembly includes a cover assembly and a cover. The cover, which can also be known as a tarpaulin, is fixed onto the cover assembly which is fixed onto a compartment. The cover is generally a soft material, so a technical problem needed to be solved is how to fix the soft materials with the compartment. Additionally, another problem needed to be solved is how to adjust of the tightness of the fixed cover.